NEXT is a 7-year longitudinal assessment of a representative sample of U.S. adolescent and young adults starting at grade 10. The goals of the NEXT longitudinal study include: to identify the trajectory of adolescent health status and health behaviors from mid-adolescence through the post high school years; to examine individual predictors of the onset of key adolescent risk behaviors and risk indicators during this period; to identify genetic, personal, family, school, and social/environmental factors that promote or sustain positive health behaviors; to identify transition points in health risk and risk behaviors and changes in family, school, and social/environmental precursors to these transitions, and to examine the role of potential gene-environment interactions in the development of health status and health behaviors.